The present invention relates to a device for rotating a container such as a bottle, can or the like while transporting the same rectilinearly which is best adapted for use with a bottle inspection device or the like.
In general, in a bottle inspection device for inspecting the whole surface of each bottle, each bottle is revolved along a circular path while it is rotated about its axis when passing through an inspection zone. In the inspection zone, a light source and a camera are used to inspect flaws and foreign matters of each bottle.
An example of a device for rotating bottles while they are transported will be described with reference to Japanese Laid-Open Utility Model No. 53099/1983. Such device is used with a bottle inspection device and comprises a turntable with a supporting shaft coupled through a reduction gear to a motor. The outer periphery of the turntable is formed with a plurality of supporting mechanism for supporting bottles. Each supporting mechanism includes a cylindrical support with a pulley attached to the lower end thereof. An endless travelling belt is disposed along the path of each supporting mechanism within an inspecting region of the bottle inspection device. When each supporting mechanism passes through the inspecting region, it is rotated about its axis because the pulley of each support is brought into contact with the endless travelling belt.
The upper portion of the support is diverged upwardly to form an enlarged head portion. A suction cup for sucking and holding a bottle is disposed within the enlarged head portion and is communicated with a vacuum pump. As the vacuum pump is operated, the elastic deformations of the peripheral surface of the suction cup occur so that the suction cup is brought into intimate contact with the bottom of a bottle, whereby the bottle is held on the surface of the support in a stable manner.
However, in the device of the type described above, as the bottles are revolved along a circular path, a centrifugal force is exerted to each bottle and consequently the bottles tend to fall down radially outwardly. As a result, in order to prevent the radial outward fall of the bottles there must be provided the suction cups for sucking and holding the bottles, a vacuum pump as a negative pressure source for supplying a negative pressure to the suction cups and electromagnetic valves. Therefore, the device itself becomes very complex in construction and furthermore since a large number of component parts are required, the device becomes very expensive.
In addition, in the inspection zone, a light source and a camera are so disposed that a bottle to be inspected passes betweenthem. The camera must be mounted on the turntable, which has no sufficient installation space, in such a way that the rotation of the turntable is not transmitted to the camera. Therefore it is difficult to mount a plurality of cameras on the turntable. Accordingly, only one camera is normally mounted. However, when only one inspection camera is mounted, its field of view is limited and a bottle to be inspected must be rotated once (through 360 degrees about its axis) in a narrow field of view of the inspection camera. As a consequence, the rotational speed of the bottle supporting mechanism must be increased considerably so that the whole surface inspection of the bottles cannot be accomplished in a satisfactory manner.
Moreover, there is a problem that when the shape and size of the bottles and their bottoms are varied, the suction cups cannot suck and securely hold the bottles.